Technologies have been developed for diagnosing whether pulmonary nodules are benign or malignant. For example, by observing the shape and size of probable pulmonary nodules over time using CT images obtained by means of an X-ray CT scanner, focused regions likely to turn malignant have been detected. However, in order to accurately identify them as cancer, diagnosis with combining results of functional tests by means of SPECT or PET has become necessary.
Moreover, perfusion tests using an X-ray CT scanner have been performed. Perfusion testing is a method of imaging a subject in which a contrast agent has been injected by means of an X-ray CT scanner and diagnosing based on imaging results.